1. Technical Field
The present invention relates to an image information detecting apparatus.
2. Description of the Related Art
At present, optical discs (for example, a CD (Compact Disc), a DVD (Digital Versatile Disc), etc.) are prevailing as recording media for recording/reproducing of information. Recently, an optical disc is additionally proposed that has a color changing layer (a photo-sensitive layer, a heat-sensitive layer, etc.) that changes the color thereof with the light intensity or heat of a laser light beam and can form characters, figures, images, etc., (hereinafter, “images”). Referring to FIG. 8, an example of the structure of an optical disc 100 that can form images is described. The optical disk 100 is structured by laminating a protecting layer 101, a color changing layer 102, and a reflecting layer 103. The color changing layer 102 consists of a photo-sensitive material or a heat-sensitive material that changes (for example, from transparent to colored, etc.) the visible properties thereof (color (color tone, brightness, chroma), reflectance, transmittance, optical obfuscation, etc.) with the light intensity or heat of a laser light beam.
An optical disc apparatus (hereinafter, “optical disc image forming apparatus”) is present that applies a laser light beam based on data in a bit map format from, for example, a host computer, etc., to form an image on the color changing layer 102. More specifically, the optical disk image forming apparatus converts the data from, for example, the host computer into image data indicating information of the light-dark state (for example, being dark indicates being colored and being light indicated being colorless) of each dot constituting the image corresponding to the shape of the optical disk 100. Based on the image data, the optical disc image forming apparatus applies a laser light beam at a level with which an image can be formed and a laser light beam at a level with which no image can be formed. A typical optical disc image forming apparatus can be an optical disc image forming apparatus formed by adding an image forming function to an optical disc apparatus that records/reproduces information to/from a recording layer (not shown) of the optical disc formed with grooves and lands thereon. Therefore, the optical disc image forming apparatus can execute various types of servo control incorporated in the optical disc apparatus. The optical disc image forming apparatus executes servo control such as, for example, focus control to focus the laser light beam on the color changing layer 102 in the optical axis direction of the laser light beam (hereinafter, “focusing direction”), thread control to apply the laser light beam in the radial direction of the optical disc 100 (hereinafter, “tracking direction”) from the inner circumference side to the outer circumference side, and spindle control to rotate the optical disc 100 synchronizing the application of the laser light beam. When an image forming is executed to the optical disc 100, the tracking control may generally become unstable being attributed to: the difference in position between the recording layer and the color changing layer 102 in the focusing direction; the light absorption of the color changing layer 102; and so forth. Therefore, the tracking control is stopped. The optical disc image forming apparatus thereafter executes application of the laser light beam and the servo control based on the data from the host computer, etc., as above. Thereby, the image indicated by the data can be formed in the color changing layer 102 of the optical disc 100. In an optical disc image forming apparatus shown in, e.g., Patent Document 1, image forming is executed forming a laser light beam at a predetermined vibration frequency in the tracking direction to make the selectivity of the contrast of the image more excellent. As above, an optical disc image forming apparatus that can form an image in the color changing layer 102 based on data from a host computer, etc., has been proposed recently.
A typical conventional optical disc image forming apparatus as above can be an apparatus disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2004-5847.
However, in a conventional optical disc image forming apparatus as above, it is difficult to detect information indicating the image (hereinafter, “image information”) from the color changing layer 102 after the image has been formed therein. Therefore, the image information cannot be detected from the color changing layer 102 after the image has been formed therein. Thereby, various problems may arise. For example, when an image is formed in the color changing layer 102 in the state where data to form the image is not stored in a host computer, etc., or a storage apparatus of an optical disc image forming apparatus, an identical image may not be able to be formed on another optical disc. Otherwise, when an identical image is formed in another optical disc image forming apparatus, an identical image may not be able to be formed if data to form the image cannot be obtained (for example, a recording medium recorded with the data to form the image, or data communication, etc.). Otherwise, in the case of deleting of or overwriting on the image formed on the color changing layer 102, an attempt to reproduce the image after the deleting or overwriting might not have been successful without detecting the image information to be stored in advance in a storage apparatus. Otherwise, forming of the image may be stopped because the optical disc image forming apparatus has received some influence (for example, an impact, shutdown of power supply, etc.) during the forming of image to the color changing layer 102. In this case, to form the image again from the dot at the time of stopping, the optical disc image forming apparatus must detect data to form the image on dots after the dot from the data from the host computer, etc. However, because the image information cannot be detected from the color changing layer 102 in which the image has been formed, the optical disc image forming apparatus may not detect the data to form the image onto the dots after the dot at the time of the stopping. Therefore, excellent image forming may not be executed.